Hybrid neural network and autoencoder

ABSTRACT

A physics-influenced deep neural network (PDNN) model, or a deep neural network incorporating a physics-based cost function, can be used to efficiently denoise sensor data. To generate the PDNN model, noisy sensor data is used as training data input to a deep neural network and training output is valuated with a cost function that incorporates a physics-based model. An autoencoder can be coupled to the PDNN model and trained with the reduced-noise sensor data which is output from the PDNN during training of the PDNN or with a separate set of sensor data. The autoencoder detects outliers based on the reconstructed reduced-noise sensor data which it generates. Denoising sensor data by leveraging an autoencoder which is influenced by the physics of the underlying domain based on the incorporation of the physics-based model in the PDNN facilitates accurate and efficient denoising of sensor data and detection of outliers.

TECHNICAL FIELD

The disclosure generally relates to the field of data processing, and tomodeling, design, simulation, or emulation.

BACKGROUND

In wellbore operations and other industrial operations, data output bysensors can be affected by physical phenomena such as acousticvibrations, impacts, and unexpected electrical discharges. In manysettings, the effects of these physical phenomena are mitigated using anautoencoder. In these scenarios, an autoencoder is a neural network thatreceives sensor data as input values, encodes the input values in areduced form using a learned encoding, and then decodes the encodedinput values to generate reduced-noise sensor data as its output.

BRIEF DESCRIPTION OF THE DRAWINGS

Embodiments of the disclosure may be better understood by referencingthe accompanying drawings.

FIG. 1 is an example conceptual diagram of denoising sensor data usingan autoencoder which was trained with output of a physics-informed deepneural network (PDNN).

FIG. 2 is an example conceptual diagram of denoising sensor data using atrained PDNN and a trained autoencoder.

FIG. 3 depicts a flowchart of example operations for training a PDNN andan autoencoder to denoise sensor data, where the autoencoder is trainedbased on the output of the PDNN.

FIG. 4 depicts a flowchart of example operations for training a deepneural network which incorporates a physics-based model over a series oftimesteps to generate a PDNN.

FIG. 5 depicts a flowchart of example operations for denoising sensordata with an autoencoder which was trained with reduced-noise sensordata output from a PDNN during training of the PDNN.

FIG. 6 depicts a flowchart of example operations for denoising sensordata using a trained PDNN and a trained autoencoder.

FIG. 7 depicts an example plot of sensor data output by a sensor.

FIG. 8 depicts an example plot comparing sensor data and reduced-noisesensor data using a PDNN.

FIG. 9 depicts an example plot comparing actual sensor data withreconstructed reduced-noise sensor data as determined by an autoencoderwhich was trained with reduced-noise sensor data output from a PDNNduring training.

FIG. 10 is an elevation view of a drilling system.

FIG. 11 is an elevation view of a wireline system.

FIG. 12 depicts an example computer system with a physics-based networktrainer and a sensor data noise reduction system.

DESCRIPTION OF EMBODIMENTS

The description that follows includes example systems, methods,techniques, and program flows that embody embodiments of the disclosure.However, it is understood that this disclosure may be practiced withoutthese specific details. For instance, this disclosure refers to a deepneural network in illustrative examples. Aspects of this disclosure canbe also applied to other neural networks such as a recurrent neuralnetwork or a long short-term-memory neural network. In other instances,well-known instruction instances, protocols, structures and techniqueshave not been shown in detail in order not to obfuscate the description.

Overview

A physics-influenced deep neural network (PDNN) model, or a deep neuralnetwork incorporating a physics-based cost function, can be used toefficiently denoise sensor data. The PDNN model can output aclean/denoised version of input sensor data containing noise moreefficiently than, for example, using a wavelet or a Fourier series-basedmethod. To generate the PDNN model, noisy sensor data is used astraining data input to a deep neural network and training output isvaluated with a cost function that incorporates one or morephysics-based models. By incorporating a physics-based model in the costfunction, the PDNN model can quantitatively differentiate betweendifferent physical processes and can also further distinguish thepresence of physical phenomena that are of relevance to an operationfrom irrelevant processes and system noise. Incorporating physics intothe PDNN model rather than utilizing a purely data-based approachimproves the predictive model of the PDNN for generating a reduced-noiserepresentation of sensor data.

When denoising sensor data with an autoencoder, various physicalphenomena such as collisions and uncompensated vibration can reduce theaccuracy of the autoencoder. To mitigate the inaccuracies which mayresult from denoising sensor data with an autoencoder alone, anautoencoder can be coupled to the PDNN model. The autoencoder can betrained with the reduced-noise sensor data which is output from the PDNNduring training of the PDNN. By training the autoencoder with the outputfrom the PDNN, the input data which the autoencoder is trained toreconstruct is preprocessed, reduced-noise sensor data rather than theraw sensor data. The trained autoencoder can thus effectively denoiseraw sensor data by reconstructing the reduced-noise sensor data from theraw sensor data received as input. Alternatively, a denoisingautoencoder trained on a separate set of sensor data (i.e., data thatwas not output from the PDNN during training) can be used to denoisesensor data, where the output of the trained PDNN is the input for thetrained autoencoder. The autoencoder can also detect outliers in thesensor data based on the reconstructed reduced-noise sensor data whichit generates. Denoising sensor data by leveraging an autoencoder whichis influenced by the physics of the underlying domain based on theincorporation of the physics-based model in the PDNN, which can becoupled to the autoencoder either during training or during use,facilitates accurate and efficient denoising of sensor data anddetection of outliers.

Example Illustrations

FIG. 1 is an example conceptual diagram of denoising sensor data usingan autoencoder which was trained with output of a PDNN. The PDNN is adeep neural network which incorporates a physics-based model fordetermining reduced-noise sensor data, where the physics-based model isalso included in the cost function used to evaluate the output of thePDNN during training FIG. 1 depicts a training system 102 and anautoencoder production system 122. The training system 102 includes aphysics-based network trainer (“network trainer”) 120. The networktrainer 120 trains a deep neural network 110 with a physics-based costfunction to generate the PDNN (hereinafter the “PDNN 110”). The PDNN 110can include any number of layers, which may be dense layers,convolutional layers, pooling layers, normalization layers, etc. Thenetwork trainer 120 also trains an autoencoder 111. The autoencoder 111can be a denoising autoencoder which comprises any number of denselayers for encoding and decoding. The network trainer 120 uses sensordata 104 captured during a downhole hydrocarbon recovery operation fortraining the PDNN 110. The network trainer 120 trains the autoencoder111 with the output of the PDNN 110 which is produced during training togenerate a trained autoencoder 126. The trained autoencoder 126 isdeployed to a sensor data noise reduction system 132 of the autoencoderproduction system 122.

The training system 102 obtains the sensor data 104 collected during ahydrocarbon recovery operation. For example, the sensor data 104 mayinclude fluid velocity data, pressure data, temperature data, fluidviscosity data, fluid density data, weight on bit data, drill bitrotational velocity data, etc. The sensor data 104 may be retrieved bythe training system 102 or communicated to the training system 102(e.g., by downhole components coupled to sensors of a drilling system).Once the sensor data 104 is available, the network trainer 120 can trainthe PDNN 110 with a subset of sensor data 104, such as a training set108 of the sensor data 104 (“sensor data 108”). A converter 106 may beused to convert the sensor data 104 and/or the sensor data 108 to anormalized form prior to training the PDNN 110. For example, theconverter 106 can be used to convert floating point data to a normalizedvalue ranging from 0 to 1.

The network trainer 120 can use any training method to train the PDNN110. For instance, the network trainer 120 can train the PDNN 110 usingbackpropagation. The PDNN 110 evaluates reduced-noise sensor data 109output during training with a cost function which incorporates aphysics-based model. A physics-based model can be incorporated in thecost function used to evaluate output of the PDNN 110 because aphysics-based model is similar to a regularization component which mayconventionally be used to evaluate output of a deep neural networkduring training Generally, the physics-based cost function can berepresented as shown in Equation 1, where C represents a cost functionvalue, P represents a solution to a physics-based model, and Drepresents a data-based value.C=P+D  (1)

Specifically, the cost function used for evaluating output of the PDNN110 can be represented as depicted below in Equation 2, where thephysics-based model ƒ(z) is a differentiable physics-based function, λis multiplier value that can be similar to or equal to a Lagrangemultiplier, z is any value or set of values based on output from asensor (i.e., the sensor data 108), y represents reduced-noise sensordata (e.g., the reduced-noise sensor data 109), and Ω represents thedomain space on which z is defined. The physics-based function ƒ(z) canbe a physics-based model in the oil and gas domain. Examples ofphysics-based models which can be incorporated as the physics-basedfunction ƒ(z) include Burger's equation, Darcy's law, and a hydraulicfracturing model equation.E(y)=∥y−z∥ _(L) ₂ _((Ω)) ²+λƒ(z)  (2)

To recover the reduced-noise sensor data 109 from the sensor data 108,the PDNN 110 determines values of the reduced-noise sensor data whichminimize a noise component of the sensor data 108. The reduced-noisesensor data 109 can be determined by solving the partial differentialequation (PDE) corresponding to Equation 2 through constrainedoptimization as a function of space x and time t with the initialcondition y(x,0) and boundary conditions y(0,t) and y(L,t) placed on y.This minimization of the noise component can be represented with theconstrained optimization problem for cost function minimizationrepresented by Equation 3, where E_(Ω) ^(z)(y) represents a cumulativevalue of E(y) over the domain space Ω. Equation 3 is subject to a noiseconstraint which is represented by Equation 4, where σ is a variancevalue, y−z is an error with the prescribed noise value, and |y−z|²represents a mean square error value.E(y)=argmin_(z)(E _(Ω) ^(z)(y))  (3)|y−z| ²=σ²  (4)

The PDNN 110 can solve Equation 3 as constrained by the noise constraintrepresented in Equation 4 using any one or more optimization techniques,such as gradient descent, simulated annealing, Bayesian optimization,genetic algorithms, etc. The reduced-noise sensor data 109, or y, isrecovered as the solution to Equation 3 as constrained by Equation 4. Insome implementations, the multiplier λ can be changed to control thequantitative effect on the cost function value E(y) which thephysics-based function ƒ(z) has relative to the data-driven value y−z.As the value of λ increases, the effect of the physics-based functionƒ(z) increases in dominance and can play a greater role in filtering forthe minimization.

The physics-based network trainer 120 can train the PDNN 110 iterativelybased on evaluation of the reduced-noise sensor data 109 by using thephysics-based cost function represented in Equation 2. For instance, thePDNN 110 may establish a cost value threshold. If the value of thephysics-based cost function calculated based on one or more sensor data108 inputs and reduced-noise sensor data 109 outputs exceeds thethreshold, the weights associated with neuron connections of the PDNN110 can be adjusted before re-computing the reduced-noise sensor data109 outputs. Training of the PDNN 110 can advance to the next set of oneor more sensor data 108 inputs based on the value of the physics-basedcost function satisfying the cost value threshold. The physics-basednetwork trainer 120 can then pass the reduced-noise sensor data 109 tothe autoencoder 111 for training.

The network trainer 120 trains the autoencoder 111 with thereduced-noise sensor data 109 passed from the output of the PDNN 110during training. Training the autoencoder 111 with the reduced-noisesensor data 109 allows the autoencoder 111 to learn to reconstruct areduced-noise representation of the sensor data 104 when receiving rawsensor data as input. The network trainer 120 can train the autoencoder111 after the PDNN 110 has been trained or during training of the PDNN110. For instance, the network trainer 120 can train the PDNN 110 untileach data point of the reduced-noise sensor data 109 has been obtainedbefore training the autoencoder 111 with the reduced-noise sensor data109. Alternatively, the network trainer 120 can train the autoencoder111 as the reduced-noise sensor data 109 output from the PDNN 110 isobtained, where the training of the PDNN 110 and adjustment of neuronconnection weights of the PDNN 110 may continue essentially in parallelwith training of the autoencoder 111. The network trainer 120 can thustrain the autoencoder 111 and the PDNN 110 “simultaneously.”

During training of the autoencoder 111, the autoencoder 111 receives thereduced-noise sensor data 109 at an input layer and applies one or moreencode layers to the reduced-noise sensor data to result in an encodedrepresentation of the reduced-noise sensor data 109. The autoencoder 111then applies one or more decode layers to the encoded representation ofthe reduced-noise sensor data 109 to produce decoded reduced-noisesensor data. The autoencoder 111 generates reconstructed reduced-noisesensor data 128 based on the decoded reduced-noise sensor data, wherethe reconstructed reduced-noise sensor data 128 is the output of theautoencoder 111 during training. The autoencoder 111 can leverage anycost function for evaluating the reconstructed reduced-noise sensor data128 output during training to determine if weights of neuron connectionsbetween encode and decode layers should be adjusted. For instance, theautoencoder 111 can use a mean squared error cost function. The networktrainer 120 can train the autoencoder 111 on the reduced-noise sensordata 109 until the autoencoder 111 satisfies one or more trainingcriteria, such as a cost threshold enforced for the reconstructedreduced-noise sensor data 128 output by the autoencoder 111. Once theautoencoder 111 has been trained and the trained autoencoder 126results, the trained autoencoder 126 is deployed to the sensor datanoise reduction system 132 of the autoencoder production system 122.

The trained autoencoder 126 is used to denoise sensor data 121, wherethe sensor data 121 is raw sensor data which can be at least a subset ofthe sensor data 104. An input layer of the trained autoencoder 126receives the sensor data 121. The trained autoencoder 126 applies theencode and decode layers to the sensor data 121 to generatereconstructed reduced-noise sensor data 124. The reconstructedreduced-noise sensor data 124 is a reduced-noise representation of thesensor data 121 which the trained autoencoder 126 reconstructs based onthe reduced-noise sensor data 109 on which the trained autoencoder 126learned. Because the trained autoencoder 126 was trained with thereduced-noise sensor data 109 output from the PDNN 110, the trainedautoencoder 126 “maps” the sensor data 121 to a reduced-noiserepresentation corresponding to the reduced-noise sensor data 109 whenreconstructing the sensor data 121 to produce the reconstructedreduced-noise sensor data 124.

The trained autoencoder 126 can also detect outliers 130 based on thereconstructed reduced-noise sensor data 124. The trained autoencoder 126can detect the outliers 130 by comparing the sensor data 121 with thereconstructed reduced-noise sensor data 124. For instance, the trainedautoencoder 126 may compare each data point of the reconstructedreduced-noise sensor data 124 which it generates with the correspondingdata point of the sensor data 121 to determine if a difference betweenthe data points exceeds a reconstruction difference threshold. If thedifference exceeds the reconstruction difference threshold, the trainedautoencoder 126 indicates that the data point of the sensor data 121and/or the reconstructed reduced-noise sensor data 124 is as an outlier.For instance, the trained autoencoder 126 may indicate after generatinga reconstructed reduced-noise sensor data point that the data point isan outlier. The sensor data noise reduction system 132 can thenassociate a label or tag with the data point in the sensor data 121and/or the reconstructed reduced-noise sensor data 124 which indicatesthat the sensor data point is an outlier. As an example, a normalizedvalue of a fluid velocity in the sensor data 121 may have a value of[0.53], while a corresponding reconstructed fluid velocity value in thereconstructed reduced-noise sensor data 124 may have a value of [0.69].If a reconstruction difference threshold is established as 0.1, then thetrained autoencoder 126 can indicate the fluid velocity value is anoutlier. The sensor data noise reduction system 132 may discard theoutliers 130 from the sensor data 121 and/or the reconstructedreduced-noise sensor data 124, exclude the outliers 130 from the sensordata 121 and/or the set of reconstructed reduced-noise sensor data 124generated from use of the trained autoencoder 126, etc.

FIG. 2 is an example conceptual diagram of denoising sensor data using atrained PDNN and a trained autoencoder. As depicted in FIG. 1, thenetwork trainer 120 trains the PDNN 110 to denoise sensor data 108,where the PDNN 110 leverages a physics-based model and a physics-basedcost function which incorporates the physics-based model. Duringtraining, the PDNN 110 generates and outputs reduced-noise sensor data109. Training the PDNN 110 with the sensor data 108 generates a trainedPDNN 216 which is deployed to a PDNN production system 212. However, inthis example, the reduced-noise sensor data 109 output during trainingof the PDNN 110 is not input to an autoencoder for training FIG. 2depicts an example in which a trained autoencoder 226 was trained usinga data set different from the reduced-noise sensor data 109. Forinstance, the trained autoencoder 226 may have been trained with asubset of the sensor data 104, such as the sensor data 108, or with adifferent set of sensor data. The operations subsequently describedoccur after the PDNN 110 has been trained based on evaluation of aphysics-based cost function as described in reference to FIG. 1 anddeployed to the PDNN production system 212 as the trained PDNN 216.

The trained PDNN 216 of the PDNN production system 212 receives sensordata 214 as input. The sensor data 214 may be, for example, a subset ofthe sensor data 104. The trained PDNN 216 incorporates an optimal set ofweights for the neuron connections which were determined based onsolving the constrained optimization problem represented above asEquations 3 and 4 to generate the reduced-noise sensor data 109 duringtraining of the PDNN 110, where the PDNN 110 evaluated the reduced-noisesensor data 109 based on valuation of the physics-based cost functionrepresented above as Equation 2. The trained PDNN 216 generatesreduced-noise sensor data 218 from the sensor data 214 (i.e., bydetermining a solution to the constrained optimization problem), whichis the output of the PDNN 216. The reduced-noise sensor data 218 is thenpassed to the autoencoder production system 122 and used as input to thetrained autoencoder 226 of the sensor data noise reduction system 132.An input layer of the trained autoencoder 226 receives the reduced-noisesensor data 218. The trained autoencoder 226 applies one or more encodeand decode layers to the reduced-noise sensor data 218 to generatereconstructed reduced-noise sensor data 224 as similarly described inreference to FIG. 1. The reconstructed reduced-noise sensor data 224 isthe output from the trained autoencoder 226.

As similarly depicted in FIG. 1, the trained autoencoder 226 can detectoutliers 230 based on the reconstructed reduced-noise sensor data 224.The trained autoencoder 226 can detect the outliers 230 by comparing thesensor data 214 with the reconstructed reduced-noise sensor data 224.For instance, the trained autoencoder 226 may compare each data point ofthe reconstructed reduced-noise sensor data 224 which it generates witha corresponding data point from the sensor data 214 to determine if adifference between the data points exceeds a reconstruction differencethreshold. If the difference exceeds the reconstruction differencethreshold, the trained autoencoder 226 indicates that the data point hasbeen identified as an outlier. For instance, the trained autoencoder 226may indicate after generating a reconstructed reduced-noise sensor datapoint that the data point is an outlier. The sensor data noise reductionsystem 132 can then associate a label or tag with the data point in thesensor data 214 and/or the reconstructed reduced-noise sensor data 224which indicates that the sensor data point is an outlier. The sensordata noise reduction system 132 may discard the outliers 230 from thesensor data 214 and/or reconstructed reduced-noise sensor data 224,exclude the outliers 230 from the sensor data 214 and/or the set ofreconstructed reduced-noise sensor data 224 which ultimately resultsfrom use of the trained autoencoder 226, etc.

FIG. 3 depicts a flowchart of example operations for training a PDNN andan autoencoder to denoise sensor data, where the autoencoder is trainedbased on the output of the PDNN. As described in reference to FIGS. 1and 2, the PDNN is a deep neural network which incorporates aphysics-based cost function based on which the PDNN evaluatesreduced-noise sensor data which it generates, where the deep neuralnetwork is “transformed” to a PDNN as a result of training based onevaluation of the physics-based cost function. The example operationsrefer to a physics-based network trainer (“network trainer”) asperforming the depicted operations for consistency with FIG. 1, althoughnaming of software and program code can vary among implementations.Though the example operations depict the network trainer as trainingboth the PDNN and autoencoder iteratively, the network trainer may trainthe PDNN before training the autoencoder. For instance, the networktrainer can first train a deep neural network to generate the PDNN andcan subsequently train the autoencoder based on the output from the PDNNwhich was generated during training.

At block 301, the network trainer obtains sensor data. The networktrainer can obtain sensor data directly from sensors. For example, thesensor data may be voltage values from an electromagnetic receiver thatare then directly transmitted to the network trainer. Alternatively, thenetwork trainer can obtain the sensor data through calculations orderivations based on other sensor data. For example, the sensor data canbe fluid acceleration values derived from fluid velocity values whichare measured by a sensor. The network trainer may also obtain the sensordata from a database which stores sensor data and/or simulation results.

At block 302, the network trainer begins training for each trainingiteration. The network trainer can allocate any subset of the sensordata for training the PDNN and autoencoder, such as 70% of the sensordata, 75% of the sensor data, etc. The number of training iterations canbe determined based on hyperparameters defined for the PDNN (e.g., anumber of epochs and a batch size).

At block 303, the network trainer trains the PDNN based on the trainingsensor data and a physics-based cost function. The network trainerinputs training sensor data to the PDNN at each iteration. The PDNN thencan determine reduced-noise sensor data from the training sensor datathrough constrained optimization of a PDE which incorporates aphysics-based model, such as the constrained optimization problemrepresented above as Equations 3 and 4. The PDNN computes a value of thephysics-based cost function, such as the physics-based cost functionrepresented above as Equation 2, using the reduced-noise sensor data todetermine whether weights of neuron connections should be adjusted.Training of the PDNN is described in further detail in reference to FIG.4.

At block 305, the network trainer trains an autoencoder based on thereduced-noise sensor data output from the PDNN. The network trainer cantrain the autoencoder with each output from the PDNN as the PDNN outputis produced such that the PDNN and autoencoder are trained“simultaneously.” For instance, the PDNN output used to calculate avalue of the physics-based cost function based on which weights ofneuron connections within the PDNN are adjusted can additionally be usedas a training input to the autoencoder. The network trainer can trainthe autoencoder using any training method and based on evaluation of anycost function. For instance, the network trainer may train theautoencoder based on minimizing a reconstruction error which iscalculated from the reduced-noise sensor data input to the autoencoderand the reconstructed reduced-noise sensor data generated by theautoencoder. The network trainer may enforce a reconstruction errorthreshold. For example, the reconstruction error threshold may indicatea reconstruction error which, when exceeded, results in adjusting theweights of the autoencoder neuron connections before redetermining thereconstructed reduced-noise sensor data, where the same input may beused after the weights are adjusted. The network trainer can proceed tothe next training input or iteration based on the reconstructedreduced-noise sensor output satisfying the reconstruction errorthreshold.

At block 306, the network trainer determines if additional trainingiterations remain. If an additional training iteration remains,operations continue at block 302 to continue training. If an additionaltraining iteration does not remain, operations are complete, and thePDNN and autoencoder are considered to be trained.

FIG. 4 depicts a flowchart of example operations for training a deepneural network which incorporates a physics-based model over a series oftimesteps to generate a PDNN (hereinafter referred to as “training thePDNN”). The example operations refer to a physics-based network trainer(“network trainer”) and a PDNN which the network trainer trains asperforming the example operations for consistency with FIGS. 1 and 2,although naming of software and program code can vary amongimplementations.

At block 401, the network trainer begins training the PDNN at a firsttimestep. The network trainer may establish a predetermined time limitor number of timesteps for training the PDNN. For example, the networktrainer may establish the number of timesteps based on the number ofexamples in a training set of sensor data to be used for training.

At block 403, the network trainer inputs sensor data into the PDNN fortraining. The sensor data may be any data retrieved during a hydrocarbonrecovery operation. For example, the sensor data can include datacollected for fluid velocity, pressure, temperature, fluid viscosity,fluid density, weight on bit, rotational velocity, etc. The sensor datamay be retrieved from the sensors which collect the data or may becommunicated to the network trainer by components which operate or arecoupled to the sensors.

At block 405, the PDNN determines reduced-noise sensor data from thesensor data. The relationship between the sensor data, reduced-noisesensor data, and the noise affecting the sensor data can be representedas shown in Equation 5 as a function of space and time, where z is theraw sensor data, y is the reduced-noise sensor data, n is the noise, xis the spatial location, and tis the time.z(x,t)=y(x,t)+n(x,t)  (5)

To recover the reduced-noise sensor data y from the sensor data z whichis input into the PDNN, the PDNN can use an optimization technique tominimize the value of the physics-based cost function through theconstrained optimization problem represented above as Equations 3 and 4.For example, the PDNN can determine the value for a reduced-noise fluidvelocity measurement based on a fluid velocity measurement measured by asensor by using a gradient descent optimization method and a fluid flowmodel (e.g., Burgers' equation) incorporated in the cost function asƒ(z) to determine a solution to Equation 3 subject to the constraintdepicted in Equation 4. Burgers' equation can be represented byEquations 6-9, where u is a fluid velocity, v is a fluid viscosity, x isa spatial location that can be normalized to a value between 0 and 1,and t is a time value:

$\begin{matrix}{{\frac{\partial u}{\partial t} - {v\frac{\partial^{2}u}{\partial x^{2}}} + {u\frac{\partial u}{\partial x}}} = 0} & (6)\end{matrix}$ $\begin{matrix}{{u\left( {0,t} \right)} = 0} & (7)\end{matrix}$ $\begin{matrix}{{u\left( {1,t} \right)} = 0} & (8)\end{matrix}$ $\begin{matrix}{{u\left( {x,0} \right)} = {\sin\left( {\pi ϰ} \right)}} & (9)\end{matrix}$

An analytical solution to Equations 6-9 can be represented as shown inEquation 10 below. Combining Equation 5 and Equation 10 results inEquation 11, where M(x, t) is a noise multiplier value and D(x, t) is arandom distribution value.

$\begin{matrix}{u = \frac{2\pi v{\sum\limits_{n - 1}^{\infty}{a_{n}{\exp\left( {{- n^{2}}\pi^{2}vt} \right)}n\sin\left( {n\pi x} \right)}}}{a_{0} + {\sum\limits_{n - 1}^{\infty}{a_{n}{\exp\left( {{- n^{2}}\pi^{2}vt} \right)}n{\cos\left( {n\pi x} \right)}}}}} & (10)\end{matrix}$ $\begin{matrix}{{z\left( {x,t} \right)} = {\frac{2\pi v{\sum\limits_{n - 1}^{\infty}{a_{n}{\exp\left( {{- n^{2}}\pi^{2}vt} \right)}n\sin\left( {n\pi x} \right)}}}{a_{0} + {\sum\limits_{n - 1}^{\infty}{a_{n}{\exp\left( {{- n^{2}}\pi^{2}vt} \right)}n{\cos\left( {n\pi x} \right)}}}} + {{M\left( {x,t} \right)} \times {D\left( {x,t} \right)}}}} & (11)\end{matrix}$

The representation of Burgers' equation depicted as Equation 11 can beincorporated as ƒ(z) in Equations 2-4. The PDNN determines reduced-noisesensor data, such as the reduced-noise fluid velocity data, based on thesolution to Equation 3 subject to the constraint depicted in Equation 4.The reduced-noise sensor data which results is the output of the PDNN.

At block 407, the PDNN computes a value of the physics-based costfunction. The PDNN can compute the value of the physics-based costfunction represented above as Equation 2, where z is the sensor datainput to the PDNN, y is the reduced-noise sensor data output from thePDNN, and ƒ(z) is a physics-based model. For example, the physics-basedmodel can be Burgers' equation, represented above as Equations 6-9. ThePDNN can leverage the solution to the physics-based model determinedduring the optimization at block 405 when computing the value of thephysics-based cost function.

At block 409, the network trainer determines if one or more convergencecriteria have been satisfied. The network trainer can determine whetherthe convergence criteria has been satisfied based on whether thephysics-based cost function has converged. Convergence of thephysics-based cost function may be based on whether the value of thecost function is below a cost threshold. For instance, the networktrainer may enforce a cost threshold. The network trainer may determinethat the physics-based cost function has converged if the value of thecost function is below the cost threshold. If the convergence criteriaare satisfied, operations continue at block 411. If the convergencecriteria are not satisfied, operations continue at block 403, where thenetwork trainer restarts training at the current timestep tore-determine the reduced-noise sensor data from the input data.Alternatively, the previously-computed reduced-noise sensor data may beused as input to the PDNN for re-determining the reduced-noise sensordata.

At block 411, the network trainer determines if additional timestepsremain. The network trainer may determine that there are additionaltimesteps for determining reduced-noise sensor data if any timestepsremain which have not been computed. As another example, the networktrainer may determine that there are no additional timesteps to computeif a predetermined time limit is exceeded. If additional timestepsremain, operations continue at block 413, where the network traineradvances to the next timestep to continue training the PDNN. Ifadditional timesteps do not remain, operations are complete, and thePDNN model is considered to be trained.

FIG. 5 is a flowchart of example operations for denoising sensor datawith an autoencoder which was trained with reduced-noise sensor dataoutput from a PDNN during training of the PDNN. For instance, the sensordata can be denoised with an autoencoder which was trained as describedin reference to FIG. 1. The example operations refer to a trainedautoencoder as performing the depicted operations for consistency withFIG. 1, although naming of software and program code can vary amongimplementations.

At block 501, the trained autoencoder receives one or more sensor datainputs. As described with reference to FIG. 3, the sensor data may beobtained directly from sensors (e.g., an electromagnetic receiver),calculated or derived from sensor data obtained directly from sensors,or obtained from a database which stores sensor data and/or simulationresults. The trained autoencoder receives the sensor data at its inputlayer.

At block 503, the trained autoencoder determines a reconstructedreduced-noise representation of the sensor data. The trained autoencoderfirst applies one or more encode layers to the sensor data to generateencoded sensor data. The trained autoencoder then applies one or moredecode layers to the encoded sensor data to generate decoded sensordata. The trained autoencoder generates reconstructed reduced-noisesensor data based on the decoded sensor data. For instance, the trainedautoencoder may generate the reconstructed reduced-noise sensor datausing the output from the decode layer(s) directly. As another example,the trained autoencoder may generate the reconstructed reduced-noisesensor data by summing the outputs from each decode layer. Thereconstructed reduced-noise sensor data is the output of the trainedautoencoder. For example, the trained autoencoder may generate andoutput a reconstructed reduced-noise value of [0.46, 0.59] based on anactual value of [0.6, 0.73]. The reconstructed data output by thetrained autoencoder is a reduced-noise representation because theautoencoder was trained with the reduced-noise sensor data output fromthe PDNN and thus learned the features of the reduced-noise sensor dataduring training.

At block 505, the trained autoencoder identifies outliers based on thereconstructed reduced-noise sensor data output from the trainedautoencoder. The trained autoencoder can detect outliers by comparingthe sensor data input and the reconstructed reduced-noise sensor dataoutput. For example, the trained autoencoder may determine whether thedifference between a reconstructed reduced-noise sensor data point and acorresponding sensor data point exceeds a reconstruction differencethreshold. If the reconstruction difference threshold is exceeded, thetrained autoencoder can indicate that the sensor data point and/or thereconstructed reduced-noise sensor data point is an outlier (e.g., byassociating an indicator or tag with the sensor data point and/or thereconstructed reduced-noise sensor data point, generating anotification, etc.). Subsequent operations which use the sensor dataand/or the reconstructed reduced-noise sensor data can discount theidentified outliers. The outliers may alternatively be discarded (e.g.,removed from the reconstructed reduced-noise sensor data).

FIG. 6 is a flowchart of example operations for denoising sensor datausing a trained PDNN and a trained autoencoder. The sensor data can bedenoised with a PDNN and a denoising autoencoder which were trained asdescribed in reference to FIG. 2. In this example, a trained autoencoderwhich was not necessarily trained with the PDNN outputs can be used.Operations depicted at blocks 601 and 603 are performed by a trainedPDNN. Operations depicted at blocks 605-609 are performed by a trainedautoencoder. The example operations refer to a trained PDNN and atrained autoencoder for consistency with FIG. 2, although naming ofsoftware and program code can vary among implementations. The exampleoperations may occur such that the output of the trained PDNN is passedto the trained as the trained PDNN generates the output. Alternatively,the example operations may occur such that the trained PDNN accumulatesa set of reduced-noise sensor data before passing the set ofreduced-noise sensor data to the autoencoder.

At block 601, the trained PDNN receives sensor data. As described withreference to FIG. 3, the sensor data may be obtained directly fromsensors, calculated or derived from sensor data obtained directly fromsensors, or obtained from a database which stores sensor data and/orsimulation results. The PDNN receives the sensor data at its inputlayer.

At block 603, the trained PDNN determines reduced-noise sensor databased on the sensor data and a physics-based model incorporated in thetrained PDNN. The trained PDNN can recover reduced-noise sensor datafrom the sensor data by determining values of reduced-noise sensor datawhich optimize a physics-based cost function in which the physics-basedmodel is incorporated. For instance, the trained PDNN can determine areduced-noise fluid velocity measurement based on a fluid velocitymeasurement measured by a sensor by solving the constrained optimizationproblem depicted above as Equations 3 and 4 using a gradient descentoptimization method and a fluid flow model incorporated as ƒ(z), such asBurgers' equation. As an example, the trained PDNN can generate a valueof [0.5, 0.6] for reduced-noise sensor data based on an actual value ofsensor data of [0.6, 0.73] by determining the reduced-noise sensor dataas a solution to Equation 3, subject to the constraint depicted inEquation 4, using the actual values of the sensor data and Burgers'equation. The PDNN outputs the reduced-noise sensor data which resultsfrom the solution, which is then passed to the trained autoencoder.

At block 605, the trained autoencoder receives the reduced-noise sensordata output from the trained PDNN. The trained autoencoder receives thereduced-noise sensor data at its input layer. The autoencoder waspreviously trained to denoise sensor data with a set of sensor datawhich was not necessarily the same sensor data used for training thePDNN.

At block 607, the trained autoencoder determines reconstructedreduced-noise sensor data from the output of the trained PDNN. Thetrained autoencoder first applies one or more encode layers to thesensor data to generate encoded sensor data. The trained autoencoderthen applies one or more decode layers to the encoded sensor data togenerate decoded sensor data. The trained autoencoder generatesreconstructed reduced-noise sensor data based on the decoded sensordata. For instance, the trained autoencoder may generate thereconstructed reduced-noise sensor data using the output from the decodelayer(s) directly. Alternatively, the trained autoencoder may generatethe reconstructed reduced-noise sensor data by summing the outputs fromeach decode layer. The reconstructed reduced-noise sensor data is theoutput of the trained autoencoder. For example, the trained autoencodercan generate and output a reconstructed reduced-noise value of [0.46,0.59] based on a reduced-noise value of [0.5, 0.6] which was received asinput.

At block 609, the trained autoencoder identifies outliers based on thereconstructed reduced-noise sensor data output from the trainedautoencoder. The trained autoencoder can detect outliers by comparingthe reduced-noise sensor data input and the reconstructed reduced-noisesensor data output. For example, the trained autoencoder may determinewhether the difference between the reconstructed reduced-noise sensordata point and the corresponding reduced-noise sensor data point exceedsa reconstruction difference threshold. Alternatively, a sensor noisereduction system in which the autoencoder is incorporated (e.g., thesensor noise reduction system 132 in FIG. 2) may determine whether thedifference between the reconstructed reduced-noise sensor data point andthe corresponding sensor data point of the raw sensor data exceeds areconstruction difference threshold. If the reconstruction differencethreshold is exceeded, the trained autoencoder can indicate that thedata point is an outlier (e.g., by associating an indicator or tag withthe sensor data point and/or the reconstructed reduced-noise sensor datapoint, generating a notification, etc.). Subsequent operations which usethe sensor data and/or the reconstructed reduced-noise sensor data candiscount the identified outliers. The outliers may alternatively bediscarded through removal from the reconstructed reduced-noise sensordata, for example.

Mathematical Proof for Convergence of PDNN Model

To illustrate PDNN convergence for determining a value y ofreduced-noise sensor data, let ƒ(z) be the physics-based model which isincorporated into the physics-based cost function. The function ƒ(z) canbe expanded using a Taylor series expansion, where ƒ is expanded in theparameter space around a first physical parameter y as shown in Equation12 and where operations can include a second physical parameter z asshown in Equation 13, where z is a value of sensor data, y is a value ofthe reduced-noise sensor data, n is a value of a noise component of thesensor data, x is a spatial location, and t is time:

$\begin{matrix}{{f(z)} = {{f(y)} + {\frac{f^{\prime}(y)}{1!}\left( {z - y} \right)} + {\frac{f^{''}(y)}{2!}\left( {z - y} \right)^{2}} + {\frac{f^{\prime\prime\prime}(y)}{3!}\left( {z - y} \right)^{2}\ldots}}} & (12)\end{matrix}$ $\begin{matrix}{{z\left( {x,t} \right)} = {{y\left( {x,t} \right)} + {n\left( {x,t} \right)}}} & (13)\end{matrix}$

Substituting y+n for z inside the Taylor series expansion and droppingthe brackets results in Equation 14 and Equation 15:

$\begin{matrix}{{f(z)} = {{f(y)} + {\frac{f^{\prime}(y)}{1!}\left( {y + n - y} \right)} + {\frac{f^{''}(y)}{2!}\left( {y + n - y} \right)^{2}} + {\frac{f^{\prime\prime\prime}(y)}{3!}\left( {y + n - y} \right)^{2}\ldots}}} & (14)\end{matrix}$ $\begin{matrix}{{f(z)} = {{f(y)} + {\frac{f^{\prime}(y)}{1!}n} + {\frac{f^{''}(y)}{2!}n^{2}} + {\frac{f^{\prime\prime\prime}(y)}{3!}n^{2}\ldots}}} & (15)\end{matrix}$

Substituting ƒ(z) for E(z) into the PDE represented as Equation 2 aboveresults in Equation 16 shown below:

$\begin{matrix}{{{{y - z}}_{L^{2}(\Omega)}^{2} + {\lambda\left\lbrack {{f(y)} + {\frac{f^{\prime}(y)}{1!}n} + {\frac{f^{''}(y)}{2!}n^{2}} + {\frac{f^{\prime\prime\prime}(y)}{3!}n^{2}\text{...}}} \right\rbrack}} = 0} & (16)\end{matrix}$

To satisfy the above minimization, as the value of n approaches zero,the value with noise z should approach the noise-free value y. If thiscondition is satisfied, the first term of Equation 16 can become zero.In the second term of Equation 16, because the noise tends to zero, thederivative terms can be dropped, and thus ƒ(z) would equal ƒ(y).

Example Plots

FIG. 7 depicts an example plot of sensor data output by a sensor. Ahorizontal axis 701 represents a data point index value. In someimplementations, the horizontal axis can represent a different parameterdomain, such as a time value or spatial value. A vertical axis 702represents a normalized value for the sensor output. As can be seen bythe line 710 representing sensor data, considerable variation can bepresent within the sensor output data over the parameter domain spacerepresented by the horizontal axis 701.

FIG. 8 depicts an example plot comparing sensor data and reduced-noisesensor data using a PDNN. A horizontal axis 801 represents a data pointindex value. In some implementations, the horizontal axis can representa different parameter domain, such as a time value or spatial value. Avertical axis 802 represents a normalized value for the sensor data. Theplot also includes a line 810 representing reduced-noise sensor data asdetermined by a PDNN. The plot also includes a set of points, such aspoint 820, where each of the set of points represents actual sensordata. As can be seen by a comparison of the values represented by theline 810 and the set of points representing actual sensor data whichincludes the point 820, values of the reduced-noise sensor data closelytrack the median values of the actual sensor data, but are less than thegreatest and least values of the actual sensor data. The differencebetween each of the values represented by the line 810 and thecorresponding points, such as the point 820, in the set of points mayindicate whether a particular point represents an outlier. For example,the value of the reduced-noise sensor data may be 0.8 at the data indexvalue of 178, and the value of the actual sensor data represented by thepoint 820 may be 0.91. If an output difference threshold is 0.1, thenthe point 820 may represent an outlier. Outliers can be verified basedon using an autoencoder as is further depicted in FIG. 9.

FIG. 9 depicts an example plot comparing actual sensor data withreconstructed reduced-noise sensor data as determined by an autoencoderwhich was trained with reduced-noise sensor data output from a PDNNduring training. A horizontal axis 901 represents a data point indexvalue. In some implementations, the horizontal axis 901 can represent adifferent parameter domain, such as a time value or spatial value. Avertical axis 902 represents a normalized value for the sensor data. Theplot also includes a line 910 representing reconstructed reduced-noisesensor data as determined by a PDNN coupled with an autoencoder. Theplot also includes a set of points, such as points 920-923, where eachpoint of the set of points represents actual sensor data. As seen in theplot, the similarity between the reconstructed reduced-noise sensor dataand the actual sensor data can be significantly greater than 90%. Thepoints 921-923 can be detected as outliers. For example, the value ofthe reconstructed reduced-noise sensor data may be 0.75 at the dataindex value of 40, and the value of the actual sensor data representedby the point 923 may be 0.80. If the output reconstruction differencethreshold is 0.04, it can be determined that the point 923 represents anoutlier. The data representing and/or corresponding to the point 923 cansubsequently be discarded. By reducing noise and producing values usedto determine whether to discard outlier data, the autoencoder trainedbased on PDNN output facilitates detection of significant deviations insensor output data, such as the data corresponding to the points921-923. Outliers can be indicative of physical phenomena causing theoutlier behavior indicated by the points 921-923.

FIG. 10 is an elevation view of a drilling system. A drilling system1000 is configured to drill into one or more geological formations toform a wellbore 1007A, 1007B; sometimes also referred to as a borehole.The drilling system 1000 can include a drill bit 1001 and a well site1006. Various types of drilling equipment such as a rotary table, mudpumps and mud tanks (not expressly shown) can be located at the wellsurface or well site 1006. The well site 1006 can include a drilling rig1002 that can have various characteristics and features associated witha “land drilling rig.” However, other drill bits can be satisfactorilyused with drilling equipment located on offshore platforms, drill ships,semi-submersibles and drilling barges.

The drilling system 1000 can include a drill string 1003 associated withthe drill bit 1001 that can be used to rotate the drill bit 1001 in aradial direction 1005 around a bit rotational axis 1004 of form a widevariety of wellbores 1007A, 1007B, such as a generally verticalwellbore, or the wellbore 1007A, or a generally horizontal wellbore, orthe wellbore 1007B, as shown in FIG. 10. Various directional drillingtechniques and associated components of a bottom hole assembly (BHA)1020 of the drill string 1003 can be used to form a generally horizontalwellbore such as the wellbore 1007B. For example, lateral forces can beapplied to the drill bit 1001 proximate to a kickoff location 1013 toform a generally horizontal wellbore (e.g., the wellbore 1007B)extending from a generally vertical wellbore (e.g., the wellbore 1007A).Each of the wellbores 1007A, 1007B can be drilled to a drillingdistance, which is the distance between the well surface and thefurthest extent of each of the wellbores 1007A, 1007B, respectively.

The BHA 1020 can be formed from a wide variety of components. Forexample, the components 1021A, 1021B, and 1021C of BHA 1020 can include,but are not limited to the drill bit 1001, drill collars, rotarysteering tools, directional drilling tools, downhole drilling motors,reamers, hole enlargers or stabilizers. The number of components, suchas drill collars and different types of components 1021A, 1021B, 1021Cincluded in the BHA 1020 can depend upon anticipated downhole drillingconditions and the type of wellbore that will be formed by the drillstring 1003 and the drill bit 1001. In addition, the BHA 1020 caninclude sensors to provide various sensor outputs. Sensor outputs caninclude values such as fluid velocity, pressure, temperature, fluidviscosity, fluid density, weight on bit, rotational velocity, etc.

The wellbore 1007A can be defined in part by a casing string 1010 thatcan extend from the well site 1006 to a selected downhole location.Various types of drilling fluid can be pumped from the well site 1006through the drill string 1003 to the drill bit 1001. The components1021A, 1021B, and 1021C can be attached to the drill bit 1001 at anuphole end of the drill bit 1001.

Drilling fluids can be directed to flow from the drill string 1003 torespective nozzles included in the drill bit 1001. The drilling fluidcan be circulated back to the well site 1006 through an annulus 1008defined in part by an outside diameter 1012 of the drill string 1003 andan inside diameter 1011 of the casing string 1010.

FIG. 11 is an elevation view of a wireline system. Subterraneanoperations can be conducted using a wireline system 1100 in a borehole1114. A platform 1102 is positioned over the borehole 1114 in thesubterranean formation 1104. The wireline system 1100 can include one ormore logging tools 1120 that can be suspended in the borehole 1114 by aconveyance 1115 (e.g., a cable, slickline, or coiled tubing). Thelogging tool 1120 can be communicatively coupled to the conveyance 1115.The conveyance 1115 can contain conductors for transporting power to thewireline system 1100 and telemetry from the logging tool 1120 to alogging facility 1144. In some embodiments, the conveyance 1115 can beindependent of a conductor, as can be the case when using slickline orcoiled tubing. The wireline system 1100 can contain a controller 1134that contains memory, one or more batteries, and/or one or moreprocessors for performing any of the operations described above, as wellas storing sensor outputs obtained by various sensors attached to thelogging tool 1120.

In certain embodiments, the controller 1134 can be positioned at thesurface 1106, in the borehole 1114 (e.g., as part of the logging tool1120 and/or in the conveyance 1115) or both (e.g., a portion of theprocessing can occur downhole and a portion can occur at the surface).The controller 1134 can include a control system or a control algorithm.In some embodiments, a control system, an algorithm, or a set ofmachine-readable instructions can cause the controller 1134 to generateand provide an input signal to one or more elements of the logging tool1120, such as sensors 1126 disposed on pads and attached to the loggingtool 1120. The input signal can cause sensors 1126 disposed on the padsto be active or to provide output signals indicative of sensedproperties.

The logging facility 1144 can collect measurements from the logging tool1120, and can include computing facilities for controlling, processing,or storing the measurements gathered by the logging tool 1120. Thecomputing facilities included in the logging facility 1144 can becommunicatively coupled to the logging tool 1120 by way of theconveyance 1115 and can operate similarly to the controller 1134. Incertain example embodiments, the controller 1134, which can be locatedin logging tool 1120, can perform one or more functions of the loggingfacility 1144.

Variations

The flowcharts are provided to aid in understanding the illustrationsand are not to be used to limit scope of the claims. The flowchartsdepict example operations that can vary within the scope of the claims.Additional operations may be performed; fewer operations may beperformed; the operations may be performed in parallel; and theoperations may be performed in a different order. For example, theoperations depicted in blocks 303 and 305 can be performed in parallelor concurrently. It will be understood that each block of the flowchartillustrations and/or block diagrams, and combinations of blocks in theflowchart illustrations and/or block diagrams, can be implemented byprogram code. The program code may be provided to a processor of ageneral purpose computer, special purpose computer, or otherprogrammable machine or apparatus.

As will be appreciated, aspects of the disclosure may be embodied as asystem, method or program code/instructions stored in one or moremachine-readable media. Accordingly, aspects may take the form ofhardware, software (including firmware, resident software, micro-code,etc.), or a combination of software and hardware aspects that may allgenerally be referred to herein as a “circuit,” “module” or “system.”The functionality presented as individual modules/units in the exampleillustrations can be organized differently in accordance with any one ofplatform (operating system and/or hardware), application ecosystem,interfaces, programmer preferences, programming language, administratorpreferences, etc.

Any combination of one or more machine readable medium(s) may beutilized. The machine readable medium may be a machine readable signalmedium or a machine readable storage medium. A machine readable storagemedium may be, for example, but not limited to, a system, apparatus, ordevice, that employs any one of or combination of electronic, magnetic,optical, electromagnetic, infrared, or semiconductor technology to storeprogram code. More specific examples (a non-exhaustive list) of themachine readable storage medium would include the following: a portablecomputer diskette, a hard disk, a random access memory (RAM), aread-only memory (ROM), an erasable programmable read-only memory (EPROMor Flash memory), a portable compact disc read-only memory (CD-ROM), anoptical storage device, a magnetic storage device, or any suitablecombination of the foregoing. In the context of this document, a machinereadable storage medium may be any tangible medium that can contain, orstore a program for use by or in connection with an instructionexecution system, apparatus, or device. A machine readable storagemedium is not a machine readable signal medium.

A machine readable signal medium may include a propagated data signalwith machine readable program code embodied therein, for example, inbaseband or as part of a carrier wave. Such a propagated signal may takeany of a variety of forms, including, but not limited to,electro-magnetic, optical, or any suitable combination thereof. Amachine readable signal medium may be any machine readable medium thatis not a machine readable storage medium and that can communicate,propagate, or transport a program for use by or in connection with aninstruction execution system, apparatus, or device.

Program code embodied on a machine readable medium may be transmittedusing any appropriate medium, including but not limited to wireless,wireline, optical fiber cable, RF, etc., or any suitable combination ofthe foregoing.

Computer program code for carrying out operations for aspects of thedisclosure may be written in any combination of one or more programminglanguages, including an object oriented programming language such as theJava® programming language, C++ or the like; a dynamic programminglanguage such as Python; a scripting language such as Perl programminglanguage or PowerShell script language; and conventional proceduralprogramming languages, such as the “C” programming language or similarprogramming languages. The program code may execute entirely on astand-alone machine, may execute in a distributed manner across multiplemachines, and may execute on one machine while providing results and oraccepting input on another machine.

The program code/instructions may also be stored in a machine readablemedium that can direct a machine to function in a particular manner,such that the instructions stored in the machine readable medium producean article of manufacture including instructions which implement thefunction/act specified in the flowchart and/or block diagram block orblocks.

FIG. 12 depicts an example computer system with a physics-based networktrainer and a sensor data noise reduction system. The computer systemincludes a processor 1201 (possibly including multiple processors,multiple cores, multiple nodes, and/or implementing multi-threading,etc.). The computer system includes memory 1207. The memory 1207 may besystem memory or any one or more of the above already described possiblerealizations of machine-readable media. The computer system alsoincludes a bus 1203 and a network interface 1205. The systemcommunicates via transmissions to and/or from remote devices via thenetwork interface 1205 in accordance with a network protocolcorresponding to the type of network interface, whether wired orwireless and depending upon the carrying medium. In addition, acommunication or transmission can involve other layers of acommunication protocol and or communication protocol suites (e.g.,transmission control protocol, Internet Protocol, user datagramprotocol, virtual private network protocols, etc.). The system alsoincludes physics-based network trainer 1211 and sensor data noisereduction system 1213. The physics-based network trainer 1211 trains aPDNN to generate reduced-noise sensor data from raw sensor data based ona physics-based model and evaluation of a cost function withincorporates the physics-based model. The physics-based network trainer1211 may also pass the reduced-noise sensor data output from the PDNNduring training to an autoencoder to train the autoencoder to generatereconstructed reduced-noise sensor data. The sensor data noise reductionsystem 1213 facilitates denoising of sensor data by leveraging a trainedautoencoder to generate reconstructed reduced-noise sensor data and todetect of outliers in sensor data based on the reconstructedreduced-noise sensor data. Any one of the previously describedfunctionalities may be partially (or entirely) implemented in hardwareand/or on the processor 1201. For example, the functionality may beimplemented with an application specific integrated circuit, in logicimplemented in the processor 1201, in a co-processor on a peripheraldevice or card, etc. Further, realizations may include fewer oradditional components not illustrated in FIG. 12 (e.g., video cards,audio cards, additional network interfaces, peripheral devices, etc.).The processor 1201 and the network interface 1205 are coupled to the bus1203. Although illustrated as being coupled to the bus 1203, the memory1207 may be coupled to the processor 1201.

While the aspects of the disclosure are described with reference tovarious implementations and exploitations, it will be understood thatthese aspects are illustrative and that the scope of the claims is notlimited to them. In general, techniques for denoising sensor data usinga deep neural network incorporating a physics-based cost function and anautoencoder as described herein may be implemented with facilitiesconsistent with any hardware system or hardware systems. Manyvariations, modifications, additions, and improvements are possible.

Plural instances may be provided for components, operations orstructures described herein as a single instance. Finally, boundariesbetween various components, operations and data stores are somewhatarbitrary, and particular operations are illustrated in the context ofspecific illustrative configurations. Other allocations of functionalityare envisioned and may fall within the scope of the disclosure. Ingeneral, structures and functionality presented as separate componentsin the example configurations may be implemented as a combined structureor component. Similarly, structures and functionality presented as asingle component may be implemented as separate components. These andother variations, modifications, additions, and improvements may fallwithin the scope of the disclosure.

Use of the phrase “at least one of” preceding a list with theconjunction “and” should not be treated as an exclusive list and shouldnot be construed as a list of categories with one item from eachcategory, unless specifically stated otherwise. A clause that recites“at least one of A, B, and C” can be infringed with only one of thelisted items, multiple of the listed items, and one or more of the itemsin the list and another item not listed.

Example Embodiments

Example embodiments include the following:

A method comprises training a deep neural network (DNN) based on sensordata and a cost function, wherein the cost function incorporates aphysics-based model. Reduced-noise sensor data are determined with theDNN during training of the DNN. The reduced-noise sensor data are passedto an autoencoder. The autoencoder is trained based on the reduced-noisesensor data to generate a trained autoencoder, wherein the autoencoderoutputs a reconstructed representation of the reduced-noise sensor data.

The method further comprises inputting at least a subset of the sensordata into the trained autoencoder and generating a reconstructedreduced-noise representation of the sensor data with the trainedautoencoder.

The method further comprises detecting at least a first outlier in thesensor data based, at least in part, on comparing the sensor data andthe reconstructed reduced-noise representation of the sensor data.

The cost function comprises a cost function of the formE(y)=∥y−z∥ _(L) ₂ _((Ω)) ²+λƒ(z),wherein ƒ(z) is the physics-based model, λ is a multiplier value, z is avalue of the sensor data, U is a domain space on which z is defined, andy is the reduced-noise sensor data.

Training the DNN and training the autoencoder are performedsimultaneously.

Determining reduced-noise sensor data with the DNN comprises determiningthe reduced-noise sensor data as a solution to a partial differentialequation (PDE) through constrained optimization, wherein the PDEincorporates the physics-based model.

The physics-based model comprises a differentiable physics-basedfunction in the oil and gas domain.

The physics-based model comprises at least one of Burgers' equation,Darcy's law, and a hydraulic fracturing model equation.

The sensor data comprises at least one of fluid velocity data, pressuredata, temperature data, fluid viscosity data, fluid density data, weighton bit data, and drill bit rotational velocity data.

One or more non-transitory machine-readable media comprise program codefor denoising sensor data, the program code to, based on receivingsensor data, input at least a first subset of the sensor data into adeep neural network (DNN). A first set of reduced-noise sensor data isgenerated based, at least in part, on the first subset of the sensordata and a physics-based model. The first set of reduced-noise sensordata is evaluated based on a calculation of a value of a cost function,wherein the cost function incorporates the physics-based model. Atrained DNN is generated from the DNN based on evaluation of the firstset of reduced-noise sensor data.

The non-transitory machine-readable media further comprise program codeto pass the first set of reduced-noise sensor data which is outputduring generation of the trained DNN to a first autoencoder and trainthe first autoencoder based on the first set of reduced-noise sensordata to generate a first trained autoencoder.

The non-transitory machine-readable media further comprise program codeto input at least a second subset of the sensor data into the firsttrained autoencoder, determine a first set of reconstructedreduced-noise sensor data based on output of the first trainedautoencoder, and detect at least a first outlier of at least one of thesecond subset of the sensor data and the first set of reconstructedreduced-noise sensor data.

The cost function comprises a cost function of the formE(y)=∥y−z∥ _(L) ₂ _((Ω)) ²+λƒ(z),wherein ƒ(z) is the physics-based model, λ is a multiplier value, z is avalue of a first of the sensor data, Ω is a domain space on which z isdefined, and y is a value from the first set of reduced-noise sensordata.

The non-transitory machine-readable media further comprise program codeto obtain a second set of reduced-noise sensor data, wherein the secondset of reduced-noise sensor data is generated by the trained DNN, inputthe second set of reduced-noise sensor data into a second trainedautoencoder, and determine a second set of reconstructed reduced-noisesensor data based on output of the second trained autoencoder.

An apparatus comprises a processor and a machine-readable medium havingprogram code executable by the processor to cause the apparatus to traina deep neural network (DNN) based on sensor data and a cost function,wherein the cost function incorporates a physics-based model.Reduced-noise sensor data are determined with the DNN during training ofthe DNN. The reduced-noise sensor data are passed to an autoencoder. Theautoencoder is trained based on the reduced-noise sensor data togenerate a trained autoencoder, wherein the autoencoder outputs areconstructed representation of the reduced-noise sensor data.

The apparatus further comprises program code executable by the processorto cause the apparatus to input at least a subset of the sensor datainto the trained autoencoder and generate a reconstructed reduced-noiserepresentation of the sensor data with the trained autoencoder.

The cost function comprises a cost function of the formE(y)=∥y−z∥ _(L) ₂ _((Ω)) ²+λƒ(z),wherein ƒ(z) is the physics-based model, λ is a multiplier value, z is avalue of the sensor data, CI is a domain space on which z is defined,and y is the reduced-noise sensor data.

The program code executable by the processor to cause the apparatus todetermine reduced-noise sensor data with the DNN comprises program codeexecutable by the processor to cause the apparatus to determine thereduced-noise sensor data as a solution to a partial differentialequation (PDE) through constrained optimization, wherein the PDEincorporates the physics-based model.

The DNN and autoencoder are trained simultaneously.

The physics-based model comprises a differentiable physics-basedfunction in the oil and gas domain.

What is claimed is:
 1. A method comprising: training a deep neuralnetwork (DNN) based on sensor data and a cost function, wherein the costfunction incorporates a physics-based model; determining reduced-noisesensor data with the DNN during training of the DNN; passing thereduced-noise sensor data to an autoencoder; and training theautoencoder based on the reduced-noise sensor data to generate a trainedautoencoder, wherein the autoencoder outputs a reconstructedrepresentation of the reduced-noise sensor data.
 2. The method of claim1 further comprising: inputting at least a subset of the sensor datainto the trained autoencoder; and generating a reconstructedreduced-noise representation of the sensor data with the trainedautoencoder.
 3. The method of claim 2 further comprising detecting atleast a first outlier in the sensor data based, at least in part, oncomparing the sensor data and the reconstructed reduced-noiserepresentation of the sensor data.
 4. The method of claim 1, wherein thecost function comprises a cost function of the formE(y)=∥y−z∥ _(L) ₂ _((Ω)) ²+λƒ(z), wherein ƒ(z) is the physics-basedmodel, λ is a multiplier value, z is a value of the sensor data, Ω is adomain space on which z is defined, and y is the reduced-noise sensordata.
 5. The method of claim 1, wherein training the DNN and trainingthe autoencoder are performed simultaneously.
 6. The method of claim 1,wherein determining reduced-noise sensor data with the DNN comprisesdetermining the reduced-noise sensor data as a solution to a partialdifferential equation (PDE) through constrained optimization, whereinthe PDE incorporates the physics-based model.
 7. The method of claim 1,wherein the physics-based model comprises a differentiable physics-basedfunction in the oil and gas domain.
 8. The method of claim 7, whereinthe physics-based model comprises at least one of Burgers' equation,Darcy's law, and a hydraulic fracturing model equation.
 9. The method ofclaim 1, wherein the sensor data comprises at least one of fluidvelocity data, pressure data, temperature data, fluid viscosity data,fluid density data, weight on bit data, and drill bit rotationalvelocity data.
 10. One or more non-transitory machine-readable mediacomprising program code for denoising sensor data, the program code to:based on receiving sensor data, input at least a first subset of thesensor data into a deep neural network (DNN), generate a first set ofreduced-noise sensor data based, at least in part, on the first subsetof the sensor data and a physics-based model; evaluate the first set ofreduced-noise sensor data based on a calculation of a value of a costfunction, wherein the cost function incorporates the physics-basedmodel; and generate a trained DNN from the DNN based on evaluation ofthe first set of reduced-noise sensor data.
 11. The non-transitorymachine-readable media of claim 10, further comprising program code to:pass the first set of reduced-noise sensor data which is output duringgeneration of the trained DNN to a first autoencoder; and train thefirst autoencoder based on the first set of reduced-noise sensor data togenerate a first trained autoencoder.
 12. The non-transitorymachine-readable media of claim 11, further comprising program code to:input at least a second subset of the sensor data into the first trainedautoencoder; determine a first set of reconstructed reduced-noise sensordata based on output of the first trained autoencoder; and detect atleast a first outlier of at least one of the second subset of the sensordata and the first set of reconstructed reduced-noise sensor data. 13.The non-transitory machine-readable media of claim 10, wherein the costfunction comprises a cost function of the formE(y)=∥y−z∥ _(L) ₂ _((Ω)) ²+λƒ(z), wherein ƒ(z) is the physics-basedmodel, λ is a multiplier value, z is a value of a first of the sensordata, Ω is a domain space on which z is defined, and y is a value fromthe first set of reduced-noise sensor data.
 14. The non-transitorymachine-readable media of claim 10, further comprising program code to:obtain a second set of reduced-noise sensor data, wherein the second setof reduced-noise sensor data is generated by the trained DNN; input thesecond set of reduced-noise sensor data into a second trainedautoencoder; and determine a second set of reconstructed reduced-noisesensor data based on output of the second trained autoencoder.
 15. Anapparatus comprising: a processor; and a machine-readable medium havingprogram code executable by the processor to cause the apparatus to,train a deep neural network (DNN) based on sensor data and a costfunction, wherein the cost function incorporates a physics-based model;determine reduced-noise sensor data with the DNN during training of theDNN; pass the reduced-noise sensor data to an autoencoder; and train theautoencoder based on the reduced-noise sensor data to generate a trainedautoencoder, wherein the autoencoder outputs a reconstructedrepresentation of the reduced-noise sensor data.
 16. The apparatus ofclaim 15, further comprising program code executable by the processor tocause the apparatus to: input at least a subset of the sensor data intothe trained autoencoder; and generate a reconstructed reduced-noiserepresentation of the sensor data with the trained autoencoder.
 17. Theapparatus of claim 15, wherein the cost function comprises a costfunction of the formE(y)=∥y−z∥ _(L) ₂ _((Ω)) ²+λƒ(z), wherein ƒ(z) is the physics-basedmodel, λ is a multiplier value, z is a value of the sensor data, Ω is adomain space on which z is defined, and y is the reduced-noise sensordata.
 18. The apparatus of claim 15, wherein program code executable bythe processor to cause the apparatus to determine reduced-noise sensordata with the DNN comprises program code executable by the processor tocause the apparatus to determine the reduced-noise sensor data as asolution to a partial differential equation (PDE) through constrainedoptimization, wherein the PDE incorporates the physics-based model. 19.The apparatus of claim 15, wherein the DNN and autoencoder are trainedsimultaneously.
 20. The apparatus of claim 15, wherein the physics-basedmodel comprises a differentiable physics-based function in the oil andgas domain.